Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
  • F25J3/0238—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 2 carbon atoms or more
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C11/00—Aliphatic unsaturated hydrocarbons
  • C07C11/02—Alkenes
  • C07C11/04—Ethylene
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
  • C07C4/02—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by cracking a single hydrocarbon or a mixture of individually defined hydrocarbons or a normally gaseous hydrocarbon fraction
  • C07C4/04—Thermal processes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
  • F25J3/0219—Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
  • F25J3/0252—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of hydrogen
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1037—Hydrocarbon fractions
  • C10G2300/1044—Heavy gasoline or naphtha having a boiling range of about 100 - 180 °C
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1037—Hydrocarbon fractions
  • C10G2300/1048—Middle distillates
  • C10G2300/1059—Gasoil having a boiling range of about 330 - 427 °C
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1081—Alkanes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/20—C2-C4 olefins
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/74—Refluxing the column with at least a part of the partially condensed overhead gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2210/00—Processes characterised by the type or other details of the feed stream
  • F25J2210/12—Refinery or petrochemical off-gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2215/00—Processes characterised by the type or other details of the product stream
  • F25J2215/62—Ethane or ethylene
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2270/00—Refrigeration techniques used
  • F25J2270/02—Internal refrigeration with liquid vaporising loop
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P30/00—Technologies relating to oil refining and petrochemical industry
  • Y02P30/40—Ethylene production

Definitions

• the present invention relates to a process for the production of low- concentration ethylene for chemical use.
• ethylene which is more than 99.8 % pure is usually used for chemical synthesis.
• This ethylene of very high purity is obtained via the cracking of various petroleum products, followed by numerous complex and expensive separation operations in order to isolate the ethylene from the other products of cracking and to obtain a product of very high purity.
• ethylene For the chemical use of ethylene, a high concentration of > 98 % is in many cases not necessary.
• the patent application WO 03/048088 describes the production of low- concentration ethylene for the chemical reaction with chlorine by means of ethane dehydrogenation.
• the ethane- loaded gas stream contains not only hydrogen and methane, but also high amounts of unconverted ethane.
• the unconverted ethane must be fed back to ethane dehydrogenation after complicated cleaning processes. This process can only use ethane as feedstock.
• a significant disadvantage is the very low concentration of ethylene - less than 60 % - as well as the fact that further components of the gas stream such as hydrogen, propylene, butadiene only allow to use the ethylene in very special processes.
• fraction C For the use of fraction C, various variants are suggested, such as combustion, recycling as feedstock without further treatment or recycling to the feedstock after hydrogenation of unsaturated components contained in fraction C.
• the recycling to feedstock without further treatment is only a hypothetic variant, since feedstock with high olefin contents leads to strong coke formation in the pyrolysis furnaces and gives a very low ethylene yield.
• the purpose of the invention is to provide a technologically simpler and more cost-effective process for producing ethylene for chemical use, in which the accumulation of by-products is eliminated.
• the invention relates to a process for the production of ethylene for chemical use starting with a hydrocarbon source according to which : a) the hydrocarbon source is subjected to a first cracking step, namely a pyro lysis step carried out in a cracking oven, thus producing a mixture of cracking products ; a) the said mixture of cracking products is subjected to a succession of treatment steps, including a compression step, which makes it possible to obtain a purified crude gas stream ; b) the purified crude gas stream is then cooled to a temperature where hydrocarbons with 6 and more carbon atoms condense so that they can be removed from the purified crude gas stream ; c) the resulting purified gas stream is afterwards supplied to one separating column, where a fraction containing hydrogen, methane and ethylene (fraction A) is separated at the head of the column and a heavy fraction
• fraction C is separated at the bottom of the column ; d) a part of the reflux of this column is supplied to a refrigeration cycle leading to a fraction enriched with ethylene (fraction B) ; e) fraction A and fraction B are separately supplied to chemical use of ethylene.
• the process according to the invention is a process starting with a hydrocarbon source (also called feedstock).
• the hydrocarbon source considered may be any known hydrocarbon source.
• the hydrocarbon source subjected to cracking (step a)) is chosen from the group consisting of naphtha, gas oil, natural gas liquid, ethane, propane, butane, isobutane and mixtures thereof.
• the hydrocarbon source is chosen from the group consisting of ethane, propane, butane and propane/butane mixtures.
• the hydrocarbon source is chosen from the group consisting of propane, butane and propane/butane mixtures.
• propane/butane mixtures may exist as such or may consist of mixtures of propane and butane.
• ethane, propane, butane and propane/butane mixtures is understood to mean, for the purposes of the present invention, products that are commercially available, namely that consist mainly of the pure product (ethane, propane, butane or propane/butane as a mixture) and secondarily of other saturated or unsaturated hydrocarbons, which are lighter or heavier than the pure product itself.
• the hydrocarbon source is subjected to a first cracking step, namely a pyro lysis step carried out in a cracking oven, thus producing a mixture of cracking pro ducts .
• first cracking step namely a pyro lysis step carried out in a cracking oven (step a)
• step a is understood to mean a conversion, under the action of heat, of the hydrocarbon source in the presence or absence of third compounds such as water, oxygen, a sulphur derivative and/or a catalyst so as to give rise to the formation of a mixture of cracking products.
• This mixture of cracking products advantageously comprises hydrogen, carbon monoxide, carbon dioxide, nitrogen, oxygen, hydrogen sulphide, organic compounds comprising at least one carbon atom and water.
• step b) the mixture of cracking products is subjected to a succession of treatment steps, including a compression step, which makes it possible to obtain a purified crude gas stream.
• the first cracking step a) is advantageously followed by step b) consisting of a succession of treatment steps among which are the steps for thermal recovery of the heat of the cracked gas, optionally organic quenching (optionally including recovery of heat through a succession of exchangers with intermediate fluids), aqueous quenching, compression and drying of the gas, alkaline washing aimed at removing at least the majority of the carbon dioxide, optionally hydrogenating the undesirable derivatives such as, for example, acetylene (to achieve advantageously a value of approximately 5 ppm of acetylene), optionally removing part of the hydrogen and/or the methane and removing hydrogen sulfide.
• step b) consisting of a succession of treatment steps among which are the steps for thermal recovery of the heat of the cracked gas, optionally organic quenching (optionally including recovery of heat through a succession of exchangers with intermediate fluids), aqueous quenching, compression and drying of the gas, alkaline washing aimed at removing at least the majority of the carbon
• the purified crude gas stream is then cooled to a temperature where hydrocarbons with 6 and more carbon atoms condense so that they can be removed from the purified crude gas stream.
• the temperature to be selected depends upon the gas composition and the gas pressure. The temperature selection is advantageously such that the benzene content in the gas after the cooling amounts to advantageously less than about 2, preferably less then about 1 and more preferably less than about 0.5 % by weight.
• the purified crude gas stream is preferably cooled to a temperature of advantageously at most 5, preferably at most 0 and more preferably at most -5 0 C. It is preferably cooled to a temperature of advantageously at least -30, preferably at least -25 and more preferably at least -20 0 C.
• the hydrocarbons condensed in step c) are returned advantageously to step b), preferably to the compression step of step b), more preferably to the last stage of compression of the compression step of step b).
• step d) the resulting purified gas stream is afterwards supplied to one separating column, where a fraction containing hydrogen, methane and ethylene (fraction A) is separated in the head of the column and a heavy fraction (fraction C) is separated at the bottom of the column
• the purified gas stream is supplied to one column, preferably after having been cooled further, where the separation of ethylene and ethane advantageously takes place.
• Ethylene, methane and hydrogen are advantageously extracted from the head of the column. All other gas components are advantageously contained in the bottom product.
• the ethylene contained in the gaseous head product (fraction A) is supplied to a chemical use of ethylene.
• the separation of ethane and ethylene is advantageously possible, despite of the presence of hydrogen, methane and higher hydrocarbons, provided that suitable technological conditions in this column are chosen.
• Ethylene, methane and hydrogen are separated in the head of column (fraction A), all other components contained in the crude gas remain in the bottom product of the column (fraction C).
• the column is advantageously equipped with a condenser for condensation of the head product, a tank for condensed head product, a boiler for heating the column as well as relevant pumps.
• Liquid ethylene is preferably used for the condensation of the head product that is produced in an ethylene refrigerator.
• the pressure of the column is advantageously adjusted to ensure that the condensation of the head product is possible, preferably by means of liquid ethylene.
• the pressure is advantageously of at least 8, preferably of at least 10 and more preferably of at least 12 bar.
• the pressure is advantageously of at most 45, preferably of at most 40 and more preferably of at most 38 bar.
• the temperature is advantageously at least -100, preferably at least -90 and more preferably at least -80 0 C at the top of column. It is advantageously at most -30, preferably at most -40 and more preferably at most -50 0 C at the top of column.
• ethylene/ethane separation is advantageously done mainly in the upper part of the column, while the separation of C3 and higher-boiling hydrocarbons is made in the lower part of the column.
• step e a part of the reflux of the separating column is supplied to a refrigeration cycle leading to a fraction enriched with ethylene (fraction B).
• a part of the reflux is supplied to a refrigeration cycle, preferably after evaporation and utilization of the refrigeration content.
• the refrigeration cycle is preferably based on ethylene.
• This amount of the part of the reflux supplied to the refrigeration cycle is advantageously taken from the refrigeration cycle in gaseous state and represents a mainly hydrogen- free, more concentrated ethylene fraction which is supplied for chemical use of ethylene (product B).
• the liquid produced by the cooling of the head product of the column serves advantageously as reflux to the column.
• the liquid produced by the cooling of the head product of the column is advantageously introduced in the refrigeration cycle, where it is mixed with the liquefied ethylene of the refrigeration cycle.
• the liquid ethylene is more preferably supplied to the head product condenser and evaporates. After the evaporation, the ethylene again most preferably enters the ethylene refrigeration cycle, where it is compressed by means of a compressor, before it is liquefied.
• This approach allows for the complete recovery of the cooling content of the liquid produced by the cooling of the head product of the column supplied to the ethylene refrigeration cycle.
• the amount of liquid produced by the cooling of the head product of the column supplied to the ethylene refrigeration cycle is advantageously taken from the ethylene refrigeration cycle in gaseous state downstream of the ethylene compressor of the refrigeration cycle.
• the liquid produced by the cooling of the head product of the column is advantageously almost free from hydrogen and contains less methane than the gaseous head product of the column.
• Fraction B is therefore advantageously depleted, preferably in low boilers, in hydrogen and methane by removing them as inert gas from the refrigeration cycle.
• the coupling of condensation of the overhead product of the separating column with the aid of the ethylene cooling circuit refrigeration cycle necessary for cooling allows advantageously the production of two grades of ethylene namely fraction A and fraction B.
• fraction A The quantities defined below to characterize fraction A are advantageously those for fraction A containing the inert gases taken from the refrigeration cycle.
• Fraction A advantageously contains more than 10, preferably more than 20 and more preferably more than 25 % the ethylene quantity which is contained in the total of fraction A plus fraction B.
• Fraction A advantageously contains less than 90, preferably less than 80 and more preferably less than 75 % the ethylene quantity which is contained in the total of fraction A plus fraction B.
• Fraction A advantageously contains more than 80, preferably more than 85 and more preferably more than 90 % the hydrogen quantity which is contained in the total of fraction A plus fraction B.
• Fraction A advantageously contains more than 70, preferably more than 75 and more preferably more than 80 % the methane quantity which is contained in the total of fraction A plus fraction B.
• Fraction A advantageously contains less than 50, preferably less than 45 and more preferably less than 40 % of the ethane quantity which is contained in the total of fraction A plus fraction B.
• Fraction B is characterized by a content of compounds containing at least 3 carbon atoms, advantageously less than or equal to 0.1 %, preferably less than or equal to 0.05 % and in a particularly preferred manner less than or equal to 0.01 % by volume relative to the total volume of fraction B.
• Fraction C advantageously contains at least 95 %, preferably at least 98 % and particularly preferably at least 99 % of compounds comprising at least 3 carbon atoms contained in the purified gas stream subjected to step d).
• Fraction C advantageously contains at most 1 %, preferably at most 0.8 % and particularly preferably at most 0.5 % by weight of ethylene relative to the total weight of fraction C.
• T e eavy ract on generate n t e ottom o t e co umn ract on C) contains advantageously ethane as well as hydrocarbons with three, four or five carbon atoms. Hydrocarbons with six or more carbon atoms being no longer contained in fraction C, this fraction can undergo hydrogenation without further treatment, preferably before being used as feedstock. Fraction C is therefore preferable hydrogenated and fed to the hydrocarbon source in step a).
• fraction C contains mainly ethane, in addition to small amounts of ethylene and hydrocarbons with three of four carbon atoms.
• high unsaturated compounds such as propine, butadiene, vinyl acetylene are preferably removed, otherwise these substances lead to strong coke formation in the pyrolysis furnaces.
• the hydrogenation of these strongly unsaturated compounds is more preferably made alongside with the hydrogenation acetylene in the selective hydrogenation which occurs preferably downstream of the compressor. This allows to recycle fraction C to the furnaces without further hydrogenation. If an additional hydrogenation is necessary, this is advantageously done as gas phase hydrogenation with known catalysts on the basis of palladium.
• the hydrogenation of fraction C takes therefore more preferably place together with the optional hydrogenation of acetylene allowing direct supply of fraction C to the feedstock without further hydrogenation.
• propane and/or butane as feedstock for the ethylene production
• larger amounts of propylene/butadiene accumulate as by-products in fraction C, together with the separated ethane.
• the hydrocarbons with six and more carbon atoms being already separated upstream of the separating column, it is therefore advantageously possible to hydrogenate fraction C without further treatment such as additional separation.
• the hydrogenation of fraction C is preferably done in adiabatic trickle phase reactors, more preferably with proven catalysts on the basis of palladium.
• fraction C is therefore most preferably subjected to hydrogenation in a trickle- phase reactor without additional separation and afterwards mixed with the feedstock.
• the process according to the invention can be adapted so that ethane is isolated, for example by drawing it off as an individual fraction from the bottom of the distillation column used to isolate fraction C or by separating it from the heavier hydrocarbons present in fraction C by the use of a further distillation column. After having been recovered, ethane can be burnt as fuel or valorized chemically.
• fraction A and fraction B are separately supplied to chemical use of ethylene.
• ethylene derivative compounds manufactured directly starting with ethylene such as for examples ethylene oxide, linear alpha-olefmes, linear primary alcohols, homopolymers and copolymers of ethylene, ethylbenzene, vinyl acetate, acetaldehyde, ethyl alcohol, propionaldehyde and 1,2-dichloroethane and also of compound derived there from such as for examples
• fraction A and fraction B are separately conveyed to the manufacture of at least one ethylene derivative compound.
• At least one ethylene derivative compound is understood to mean, for the purpose of the present invention, that one or more than one ethylene derivative compounds may be manufactured by the process according to the present invention.
• ethylene derivative compound is understood to mean, for the purpose of the present invention, any ethylene derivative compound manufactured directly starting with ethylene as well as any compound derived there from.
• ethylene derivative compound manufactured directly starting with ethylene is understood to mean, for the purpose of the present invention, any compound manufactured directly from ethylene.
• compound derived there from is understood to mean, for the purpose of the present invention, any compound manufactured from one compound itself manufactured from ethylene as well as any compound derived there from.
• fraction A and fraction B are both conveyed to the manufacture of 1,2-dichloroethane and optionally of any compound derived there from, optionally after having been subjected to an acetylene hydro genation.
• a particular preferred process is the one in which fraction A is conveyed to a chlorination reactor and fraction B to an oxychlorination reactor, in which reactors most of the ethylene present in the fractions A and B is converted to 1,2-dichloroethane.
• the 1,2-dichloroethane obtained is afterwards advantageously separated from the streams of products derived from the chlorination and oxychlorination reactors, preferably subjected to a DCE cracking step to produce vinyl chloride which itself is afterwards more preferably polymerized to produce PVC.
• a preferred embodiment of the process according to the invention is a process for the production of ethylene for chemical use starting with a hydrocarbon source according to which : a) the hydrocarbon source is subjected to a first cracking step, namely a pyrolysis step carried out in a cracking oven, thus producing a mixture of cracking products ; b) the said mixture of cracking products is subjected to a succession of treatment steps, including a compression step, which makes it possible to obtain a purified crude gas stream ; c) the purified crude gas stream is then cooled to a temperature where hydrocarbons with 6 and more carbon atoms condense so that they can be removed from the purified crude gas stream and afterwards returned to step b) ; d) the resulting purified gas stream is afterwards supplied to one separating column, where a fraction containing hydrogen, methane and ethylene
• fraction A is separated at the head of the column and a heavy fraction (fraction C) is separated at the bottom of the column ; e) a part of the reflux of this column is supplied to a refrigeration cycle which is an ethylene refrigeration cycle leading to a fraction enriched with ethylene (fraction B) ; e') fraction B is optionally depleted in hydrogen and methane by removing them as inert gas from the refrigeration cycle ; e") hydrogen and methane are optionally added to fraction A ; f) fraction A and fraction B are separately supplied to chemical use of ethylene ; g) fraction C is hydrogenated and fed to the hydrocarbon source in step a).
• the hydrocarbon source a is subjected to a first cracking step 1, where it is converted into a mixture of cracking products.
• the said mixtures of cracking products is afterwards subjected to a succession of treatment steps 2 including a compression step (called hereafter compressor area) in order to obtain a purified crude gas stream b.
• the purified crude gas stream b is then cooled in 3, so that the hydrocarbons with six and more carbon atoms condense, before being returned to the compressor area 2.
• the resulting purified gas stream c is afterwards separated in the column 4 into d at the head of the column and into j at the bottom of the column (fraction C).
• Fraction d containing ethylene, methane, hydrogen as well as traces of CO is then partly condensed in the condenser 5 by means of liquid ethylene i from the ethylene refrigeration cycle 6.
• the remaining gas phase e is supplied to chemical use of the ethylene contained therein (fraction A).
• the condensed liquid head product f is used as reflux to the column, part g is given to the ethylene refrigeration cycle 6 and, after the recovery of the contained cold energy, given in gaseous state as e' (fraction B) to chemical use of the contained ethylene.
• dissolved hydrogen as well as methane are separated as inert gas h in the ethylene refrigeration cycle.
• the inert gases h may be added to e.
• the bottom product j of column 4 contains ethane as well as hydrocarbons with 3 to 5 carbon atoms.
• the hydrogenation of unsaturated components contained therein takes place in the hydrogenation 7.
• the hydro genated product k is added to the feedstock a prior to cracking 1.

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• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 2008
  • 2008-06-03 EP EP08157514A patent/EP2130811A1/en not_active Ceased
• 2009
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  • 2009-05-28 MX MX2010013000A patent/MX2010013000A/es not_active Application Discontinuation
  • 2009-05-28 BR BRPI0913217A patent/BRPI0913217A2/pt not_active IP Right Cessation
  • 2009-05-28 AU AU2009253975A patent/AU2009253975A1/en not_active Abandoned
  • 2009-05-28 US US12/995,509 patent/US8173855B2/en not_active Expired - Fee Related
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• 2010
  • 2010-11-24 CO CO10147585A patent/CO6351771A2/es not_active Application Discontinuation

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